Removable terminal



Aug. 19, 1930.

F. C. HOL TZ REMOVABLE TERMINAL Filed Oct. 5, 1928 fizz/anibf FEczemb C 170K ZZ MIy m My! Patented Aug. 19, 1930 'UNITED STATES PATENT oFFlcs v COMPANY, OF SPRINGFIELD, ILLINOIS,

,A. CORPORATION OF ILLINOIS REMOVABLE TERMINAL Application filed October 5, 1928. Serial No. 310,449.

This invention relates to terminal construction and the object of the invention is the production of a removable terminal for electric meters or other devices, necessary to electrically insulate the entering conductors from the housing of such devices and, at the same'-time, give adequate protection against the entrance of dust, or similar undesirable material.

A further object of this invention is to provide a simple, practical construction, which employs a minimum number of parts and which is not only held secure when in position, but which can also be replaced with a minimum of effort.

The particular manner in which these results are obtained is best shown by reference to the following drawings, which illustrate one embodiment of my invention, in which:

Figure 1 shows a typical meter case equipped with four of my new removable terminals;

Figure 2 is a fragmentary cross-sectional view of a portion of a meter case and one removable terminal along the line 2-2 of Figure 1;

Figure 3 is a front view of the removable terminal with the incoming conductor clamping screw removed;

Figure 4 is a rear terminal;

Figure 5 is a top end view of the removable terminal; and

Figure 6 is a bottom end view of the removable terminal.

The terminal itself consists of a central conducting insertl of brass or other conducting material having an acorn shaped cross secview of the removable tion. This conducting insert is firmly moulded into an outer msulating shell 2 of V bakelite or other moulding material. In the present construction, the surface of the outer bakelite shell'consists of two concentric cylindrical surfaces 3 and 10, which are joined as shown by a conical surface 4, the surface 10 being of smaller diameter than the surface 3. A flat surfaced projecting portion 18 on the upper end of the conducting insert 1 extends out beyond the end of the outer insulating shell 2 and is provided with a transverse perin which it is foration 19 drilled at right angles the flat surface 20.

The perforation 19 is tapped to receive a standard machine screw for fastening one of the conductors of the meter apparatus.

In the opposite end of the conducting insert 1, a longitudinal hole 14 is bored, eccentrio with respect to the central axis of the conducting insert. An enlarged opening 15 is provided in the lower end of the insulating shell 2, this opening being concentric with and leading 1nto the hole 14 in the conducting insert 1. The openings 15 and 14 are for receiving an incoming conductor. A transverse hole 21 is bored into the side of the conducting insert at thepoint of greatest thickness, meeting the longitudinal hole 14. The hole 21 is tapped to receive a standard machine screw 12 for clamping the incoming conductor in hole 14. 7 Hole 14 is bored eccentric with respect to the axis of the conducting insert to obtain greater thickness of metal at the point where the hole 21 is bored, so as to increase the threaded area of the hole and thereby increase the holding power of the screw 12. I

Openings 13 and 17 are provided in the insulating shell 2 for the purpose of preventing undue strain in the bakelite if, for any reason, the terminal screw 12 is forced too tightly into position. or if, because of a loose contact at the terminal screw, considerable heat should be generated at this point, thus causing excessive expansion in the conducting material. The material which would, otherwise, be subjected to strain, or to heat, namely that directly in the vicinity of the hole 21 and that directly opposite, has been removed.

Furthermore, these openings by exposing the conducting insert 1 at the point where heat may be generated, provide better radiating surfaces, and as a result, a lower temperature is maintained and excessive strain, due to sudden expansion or contraction of the materials, is prevented.

' The meter case shown in Figures 1 and 2 and in connection with which I have chosen ratus is mounted, and a terminal chamber 23 defined by walls 8 and 16. A series of openings are provided in the walls Sand 16 for receiving removable terminals of the type described, the number of pairs of openings corresponding to the number of terminals required, each pair of openings being drilled to receive the corresponding cylindrical surfaces of the terminals. The opening 24 in the m outer wall is cylindrical, andis made slightly larger than the diameter of surface 3 of the insulating shell 2, so that the latter may readily be introduced through such opening. The

opening in the inner wall 16 between the terminal chamber 23 and the apparatus chamber of the meter case 22 has one portion large enough to receive the surface 3 of the shell 2, and another portion 26 large enough to receive the surface 10 of the shell 2. J oina ing the two portions 25 and 26 is the conical portion 27, against which the conical surface 4 of the insulating shell bears when the terminal is placed in position.

The lower 3 2 is provide at one side thereof with a conical recess 11, the purpose of which is to receive the tapered end 5 of a set screw 6,

which is threaded into a threaded hole 7 in the outside wall 8 of the terminal chamber.

To place a terminal in position, the terminal is inserted into the openings 24, 25 and 26, until the conical surface 4 en es the conical surface 27. The terminal is then rotated, if necessary, until the opening 11 is lined up to approximately correspond with the threaded hole 7 in the outer wall 8. It is to be noted that the location of the hole 7 is such that with the conical surfaces 27 and 4 in contact, the hole 11 lies a little below the hole 7. Under these conditions, upon introducing the set screw 6 into the threaded hole 7, its tapered surface 5 is forced into contact with the upper surface 9 of the recess 11, forcing the conical surface 4 into firm contact with the conical surface 27, thereby sealing the opening against the entrance of dirt or dust particles. The set screw 6 in the recess 11 also serves to prevent any possible turning of the terminal. A connection with the meter apparatus is made with the terminal by means of a machine screw threaded into the tapped hole 19. The incomin conductor is inserted through the hole 15 into the hole '14, and is clamped in position by tapped hole 21.

It will be readily appreciated that the terminal construction of my invention is extremely simple, and in making replacements, only a single unit is involved.

I do not wish to be limited to the exact construction shown, as many modifications, all within the scope of my invention, will su gest themselves to those skilled in the art.

at is considered new and is desired to (portion of the insulating shell g to engage the surface of said means of the set screw 12 threaded into the have protected by Letters Patent, is set forth in the appended claims:

1. In combination, a frame for a piece of electrical apparatus having an opening to receive a terminal, the walls of said opening being provided with an internal shoulder, and a terminal comprising a conducting member adapted for connection with an electrical conductor, and an insulating shell enclosing said conducting member and having a circumferential shoulder adapted to abut against the shoulder in said opening, and means for forcing the shoulder of said shell against the shoulder in said opening.

2. In combination, a frame for a piece of electric apparatus having a tapered opening to receive a terminal, and a terminal comprising a conducting member adapted for connection with an electrical conductor and an insulating shell enclosing said conductingmemher and having a portionofits surface conical in shape, said portion being adapted to engage .the sides of said tapered opening, and means for forcing said conical surface against the sides of said tapered opening.

3. In combination, a terminal comprising a conducting member adapted for connection with an electrical conductor and an insulating shell enclosing said conducting member and having two cylindrical surfaces of different diameters with a shoulder between such surfaces, and a frame for a piece of electrical apparatus 'having an opening having two sections of different diameters adapted to receive the two surfaces of said insulating shell, respectively, and a shoulder between said sections, and means for forcing the shoulder between said two surfaces tightly against the shoulder between said two sections;

4. In combination, a frame for a piece of electrical apparatus having an opening to receive a terminal, the walls of said opening being provided with an internal shoulder and a terminal comprising a conducting member adapted for connection with an electrical conductor and an insulating shell enclosing said conducting member and having a circumferential shoulder adapted to abut against the shoulder in said opening, and having a transverse conical recess, and a set screw in said frame having a tapered end adapt-ed conical recess force the shoulder of said shell against the shoulder in said opening.

5. The combination with an electric instrument frame having a terminal chamber defined by twowalls, each having an opening to receive a terminal. one of the walls being provided with an internal shoulder around the openingtherein, of a terminal comprising a conducting member adapted for connection with an electrical conductor, and an insulating shell enclosing said conducting member and having a adapted'to abut against the shoulder in the circumferential shoulder opening in said one wall, and having a transverse recess, and a set screw threaded into a hole in the other of said two walls adapted to enter said recess to hold the terminal in position.

6. The combination with an electric instrument frame having a terminal chamber deiined by two walls, each having an opening to receive a terminal, one of the walls being Y provided with an internal shoulder around receive a terminal, one of the walls being provided with an internal shoulder around the opening therein, of a terminal comprising a conducting member adapted for connection with an electrical conductor, and an insulate ing shell enclosing said conducting member and having a circumferential shoulder adapted to abut against the shoulder in the opening in said one wall, and a transverse conical recess, and a set screw threaded in a hole in one of said walls and having a tapered end adapted to engage the surface of said'recess to force the shoulder of said shell against the shoulder in the opening in one wall.

9. terminal comprising a conducting member having a longitudinal boring in one end for receiving an electrical conductor and having a transverse threaded hole meeting said boring for receiving a machine screw to clamp the conductor in said boring, and an insulating shell enclosing said terminal having an opening exposing the conducting member around said threaded hole, the walls of said opening being spaced a substantial distance from said screw.

9. A. terminal comprising a conducting member having a longitudinal boring in one end for receiving an electrical conductor and having a transverse threaded hole meeting said boring for receiving a machine screw to clamp the conductor in said boring, and an insulating shell enclosing said terminal having an opening exposing the conducting member diametrically opposite said threaded hole.

10. A terminal comprising a. conducting member having a longitudinal boring in one end for receiving an electrical conductor and having a transverse threaded hole meeting said boring for receiving a machine screw to clamp the conductor in said boring, and an insulating shell enclosing said terminal haw ing an opening exposing the conducting mem-- her around said threaded hole, and an open ing diametrically opposite the threaded hole exposing the conductor member on that side.

11. A terminal comprising a conducting member having an eccentric longitudinal boring in one end for receiving an electrical conductor and having a transverse hole extending through the thicker part of the wall thereof, said holebeing threaded to receive a machine screw to clamp the conductor in said boring, and an insulating shell around said conducting member and having an opening to expose the outer surface of the thinner part of the wall thereof.

12. A terminal comprising a conducting member having an eccentric longitudinal boring in one end for receiving an electrical conductor and having a transverse hole extend ing through the thicker part of the wall thereof, said hole being threaded to receive a machine screw to clamp the conductor in said boring, and an insulating shell around said conducting member and having openings exposing the outer surface thereof around the threaded hole and the surface on the opposite side of and in line with such threaded hole.

13. lln combination, a frame, a terminal adapted to be inserted into said frame and comprising a conducting member, adapted for connection with an electric conductor, and an insulating shell enclosing the conducting member and provided with an external circumferential shoulder cooperating with the m9 frame when the terminal isin position therein, and cooperative means on the frame and shell for securing the latter to the frame.

14. An electricai terminal comprising a conducting member having, at one end thereof, two concentric borings, the inner one being smaller than the outer one, means for clamping an incoming insulated conductor in said inner bore, the conductor proper being received in the smaller boring and the insulation being receive-d in the other boring, and an insulating shell formed around said terminal.

In witness whereof, I hereunto. subscribe my name this first day of @ctober, 1928.

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